Postgresql update string, add chars before and after

Question

Help pls to update a column card_num with data like:

"000001"
"000002"
..
"000200"

Need to do:

"%000001,"
"%000002,"
..
"%000200,"

Answer 1

update table set card_num = '%'||card_num||','

use || concatenation operator to leave nulls as nulls, not %, values